The present invention relates to a coupling component for a light waveguide. More particularly it relates to a coupling component for a light waveguide which has a groove arranged at the circumference and a light-sensitive transmitting and/or receiving component for coupling the optical radiation in and out of the light waveguide. A coupler for a light waveguide is already known from DE-PS 26 14 051, in which a notch or groove is partially arranged at the circumference of the light waveguide. The side flanks of the groove have smooth surfaces which are reflective. A transmitting or receiving device is arranged on the side of the light waveguide opposite the groove. The radiation in the light waveguide is partially directed at the reflective surfaces of the groove to the receiver. The radiation generated by the transmitter is coupled into the light waveguide via the reflective surface in a corresponding manner. This arrangement of a coupling component requires great precision in the production of the coupling component. The cost is also considerable, since the flanks of the groove must be very smooth, flat and reflective. The coupling of the receiving and transmitting component also requires high precision, since a portion of the coupled out optical radiation is otherwise lost in the boundary layer between the light waveguide and the connected component. Since the fibers of the light waveguide are relatively thin, the coupled receiving and transmitting component can only be mechanically loaded to a very small degree. Therefore, shaking can easily lead to breakage and accordingly to a failure of the coupling component.